In numerous applications it is necessary to impregnate or coat linear shaped materials, such as fibers, strands or textile ribbons, particularly mineral fibers such as glass fibers, with a viscous matter, such as synthetic resin.
Generally it is necessary that this deposit of matter be regularly distributed and thus the quanity of matter retained by the material must be adjusted. It is known, in order to make this adjustment, to force the impregnated materials through dies. This method of adjustment has various inconveniences.
The principal inconvenience with this method is that it does not obtain retention rates below 25% of the total mass of material and deposit. Depending on the speed of operation, the retention rate may be between 25 and 30% and it seems impossible, even when using small dies to go below these values.